Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds two genuinely useful behavioral facts the annotations do not: proximity is measured as straight-line (not travel) distance, and include_status triggers one request per resort, warning of cost/latency. It omits ordering of results and any failure behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences with zero filler; the primary behavior (nearest resorts by straight-line distance) is front-loaded and the optional cost-bearing flag follows. Nothing could be cut without losing information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description carries the burden of explaining returns, and it only partially does so: it implies a list of resorts ordered by distance plus optional lift counts, but does not say how results are ordered, truncated by limit, or shaped. Adequate but with clear gaps for a 5-parameter tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is only 40% (limit has no description anywhere, and lat/long carry only range constraints), so the description should compensate more. It does clarify that latitude/longitude define 'a point' and that include_status fetches live lift counts at a per-resort request cost, but limit and max_km semantics are left entirely to the schema or unstated.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource with scope: 'Resorts closest to a point, by straight-line distance.' The distance metric distinguishes it from routing-style tools, and it is clearly not a comparison, listing, or status tool. It stops short of naming which sibling (e.g., ski_search_resorts) to prefer when proximity is not the criterion.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Optionally fetches live open-lift counts' implies when to set include_status, and 'by straight-line distance' hints at the proximity use case. But there is no explicit when-to-use-this-vs-alternatives guidance against six siblings such as ski_open_now or ski_search_resorts, so the agent must infer routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.